Information transfer and ink particle refining system



April 22, 1969 P. A. STQWELL 3,439,650

INFCRMATION TRANSFER AND INK PARTICLE REFINING SYSTEM Filed July 12,1965 Sheet of 5 Fig l J 71 t 7.0 {8 4b INVENTOR. Philip A. g towdlv BYATTORNEY p 1969 P. A. STOWELL 3,439,650

INFORMATION TRANSFER AND INK PARTICLE REFINING SYSTEM Filed July 12,1965 Z of 5 INVENTOR.

DMH A.SJCOU)2H ATTORNEY April 22, 1969 P. A. STOWELL. 3,439,650

INFORMATION TRANSFER AND INK PARTICLE REFINING SYSTEM Filed July 12,1965 Sheet 3 of s L A 1 1 i i /L l "2 J I I {6 Ho INVENTOR. Philip A. 5iowell.

ATTORNE Y United States Patent 3,439,65tl INFORMATIGN TRANSFER AND llNKPARTICLE REFINHNG SYSTEM Philip A. Stowell, Pauli, Pa, assignor toBorg-Warner Corporation, Chicago, Ill, a corporation of lllinois FiledJuly 12, 1965, Ser. No. 471,176 Int. Cl. 30% 5/02 U.S. Cl. 118-637 7Claims ABSCT OF THE DISCLUSURE An inker station for developing apreviously charged dielectric web includes a housing for retaining theparticles and discharging them into one input connection of aVenturi-type fitting as an air stream is passed into the other inputconnection of the fitting. From the fitting the entrained material isdischarged into a cyclone separator where undesired small particles areremoved, and then into a vibrator separator which excludes unduly largeparticles and passes only particles within the desired size range backinto the housing to contact, and adhere to, the previously chargeddielectric web as it 18 pulled through a portion of the housing. Asnlifer disposed at the web exit removes excess background 1nk particlesfrom the developed web.

The design and production of a suitable inker station for anelectrostatic printer in which a page format is the end product, ratherthan a narrow strip of dielectric tape on which the information has beenimprinted, presents considerable problems. In strip printers where thewidth of the paper web is of the order of an inch, seals are generallyused at least at the input portion of the inker station so that theminute ink particles Wlll not be displaced out of the inker reservoir orhopper when the tape is run through the inker at high speeds. Even withthe best of seal arrangements there is some wear, and likewise somesmear or lack of clarity of definition in the image as the tape with theparticles adhering thereto leaves the inker. It would be desirable, inthe development of an inker for a page printer for effectively andrapidly handling the developing of a wide web of paper rather than anarrow strip, to provide such an inker station without any sealswhatever. Of course such an inker station would also find utility withstrip printers, those using narrow paper tapes.

It has become apparent in the long-term operation of strip printers thata considerable amount of debns such as dust particles, slitter dust,etc. is pulled into the inker reservoir on the dielectric web and muchof this debris is left in the ink reservoir. It is thus a primaryconsideration of the present invention to provide an lnker station inwhich the debris is not accumulated but is contrnually removed from theinker. This is in contradistinction to previously known arrangements inwhich the dust and dirt usually floats to the top of the IHKII'GSHVOII'and inhibits the proper inking of the electrostatically charged web.

Another major disadvantage found in some previous inker arrangements isthat a good definition of the image cannot be provided because thetechnology for providing ink of uniform particle size is not yetperfected. Not only is there aberration in the particle sizes but thereis satelliting in which several smaller particles may adhere to a largerparticle in the production process and retain this arrangement whendumped into the ink reservoir. Other particles of approximately the sames1ze adhere to each other to build undesirable total particle size. Inmks such as this which are made of carbon particles and resin, in thefinished product the carbon particles are sometimes 3,439,650 PatentedApr, 22, 1969 coated with a very thin resin film which completelysurrounds the carbon and thus militates against good inking action. Itis accordingly another important consideration of the present inventionto provide an ink handling system in connection with the ink reservoirwhich not only obviates these difficulties encountered with knownsystems, but actually refines and improves the ink during the particletransfer operation.

Summary of the invention The foregoing and other considerations arerealized, in a preferred embodiment of the invention, by providing aninker station which includes a housing having an upper chamber forretaining the ink particles to contact the previously charged dielectricweb and a lower reservoir chamber for collecting the particles whichfall from the upper chamber. The station includes a Venturitype fittingwith an output connection and two input connections. One of the inputconnections is coupled to the reservoir chamber so that as air underpressure is passed into the other input connection, a stream of air withconductive particles entrained therein is discharged from the outputconnection. First separation or refining means, which may be a cycloneseparator, is provided with an input connection which is coupled to theoutput connection of the Venturi-type fitting for receiving theentrained particles of desired size together with fine and coarseimpurities. Impurities refers not only to foreign matter but also toparticles smaller than, and particles larger than, the ink particlesfalling within the predetermined or desired range of particle sizes. Thefirst separation means also includes a first output connection fordischarging the fine impurities and a second output connection fordischarging both the desired particles and the coarse impurities. Afilter is coupled to the first output connection of the first separationmeans to trap the fine impurities. A second separation means is disposedso that its input portion receives both the desired and coarseimpurities from the first separation means. The second separation meansincludes means for separating the coarse particles from the particles ofdesired size and for discharging the coarse particles for receipt in acollection receptacle as the desired size particles are dischargedthrough an output port for receipt in the upper chamber of the inkerhousing. Pressure unbalance means, such as a pump, is coupled betweenthe filter and the other input connection of the Venturi-type fitting,for providing the air under pressure to the Venturi-type fitting. Thus,upon energization of the pump, the opaque inking particles arepneumatically recirculated throughout a closed system and continuallyrefined as the particles of undesired size are removed in each cycle ofmovement.

T he invention may also comprise a snitfer or suction means disposedagainst adjacent the location at which the inked web emerges from theinker station. Upon application of suction pressure to the inker thebackground ink particles are drawn from the tape as it emerges from theinker station, thus providing better contrast and a more satisfactoryprinted record.

The drawings To enable those skilled in the art to practice theinvention, the best mode contemplated for making and using the inventionwill now be described in connection with the accompanying drawings, inthe several figures of which like reference numerals identify likeelements, and in which:

FIGURE 1 is a schematic diagram indicating generally the pneumatictransfer of the inker particles around the system and the particle sizeclassification;

FIGURE 2 is a partial sectional showing, taken on a scale enlarged withrespect to that of FIGURE 1, showing the normal position of the inkparticles in the upper chamber of the inker housing as the web passes incontact with the ink particles;

FIGURE 3 is a perspective illustration of air deflecting means withinthe upper chamber of the inker housing;

FIGURE 4 is a partial sectional view showing the means for feeding theink particles across the width of the inker chamber;

FIGURE 5 is an exploded view, partly broken away, indicating thecomponents of the sniffer which are positioned adjacent the inked web;

FIGURE 6 is a side view, partly in section, of the Venturi-type fittingutilized in the system;

FIGURE 7 is a sectional view, taken along the line 77 of FIGURE 6,particularly illustrating a portion of the Venturi fitting construction;and

FIGURE 8 is a front view, partly in section, illustrating a cycloneapparatus of the type utilized in the inventive system.

General system arrangement As shown in FIGURE 1 the inker housing 10includes a reservoir 19 coupled to a first input connection 11 of aVenturi-type fitting 12. The other input connection 13 of theVenturi-type fitting is coupled to a conduit 14 for receiving air underpressure as will be described hereinafter.

The output connection 15 of the Venturi fitting is coupled throughanother conduit to a tangential input connection 17 of a firstseparation means 18, shown as a cyclone separator unit. The refiningunit 18 includes an upper outlet 20 or first connection which is coupledto a conduit 21, and a second output connection or lower outlet 22 fordischarging particulate material by gravity. The cyclone separatoroperates in a well known manner in the inventive system so that, when apressure less than atmospheric pressure is supplied from conduit 21 tothe upper output connection 20, particles of material fed inwardlythrough tube 17 and less than a predetermined mass are drawn upwardlythrough fitting 20 and out of the cyclone separator. The remainingparticles of a greater mass are thrown outward against the wall bycentrifugal forces and drop downwardly under the force of gravity to bedischarged through output port 22 into the second separation means 23.

The second refining means includes a receptacle portion 25 with a screenmesh 26 effectively dividing the receptacle into upper and lowerportions. Within actuator portion 27 a vibrator motor (not shown) ispositioned and coupled to receptacle 25 so that, responsive toenergization over input conductors 28 and 30, the receptacle 25 israpidly vibrated in the horizontal plane. This vibrating arrangement issupported on a base 31. The screen is inclined slightly downwardly tothe right, and the effect of the vibrating action is twofold. Particlesgreater than a given size will not pass through the apertures in screen26 but will be carried downwardly to the right and fall over lip 32downwardly for receipt within a collection box 33. The remaining inkingparticles, less than the predetermined size as determined by screen 26,pass through the apertures in mesh 26 and are likewise displaced to theright by the vibrating action to emerge through conduit 34 and dropdownwardly into the upper chamber 35 of the inker reservoir -10.Additional ink particles are discharged from conduit 24 into chamber 35each time the system is energized, as will be explained hereinafter. Theinker also includes an anvil 36 or reference plate for guiding thedielectric web as it passes through the inker housing to attractconductive particles to the previously charged web areas. The dielectricweb passes around a guide roller 37 and thereafter around the lowerportion of anvil 36, being pulled upwardly and deflected around theupper edge portion of the anvil to emerge from the inker housing andpass between pressure fixing rolls 38-, 40. Thus the only impetus fordielectric web displacement through the inker station is provided by thepositive driving engagement of pressure fixing rolls 38 and 40.

As the web emerges from the inker station it passes adjacent a suctionhead 41 or snifier. The sniffer is coupled over a conduit 42 to thecentral or tangential input connection 43 of another cyclone separator44, which likewise includes an upper output port 45 and a lower outputconnection coupled between collection box 46 and conduit 24, to dumpcollected particles through conduit 24 into chamber 35 each time valve47 is actuated by a control signal over conductors 74, 75.

The upper output connection 45 of cyclone separator 44 is coupled over aconduit 48 to one side of a filter 50, the other side of which iscoupled through a conduit 51 to a pump 52 which has its output sidedischarging through a conduit 53 to the atmosphere. Pump 52 ismechanically coupled as represented by the broken line 54 to a motor 55which can be energized over its input conductors 56, 57.

Considering again the first separator means or cyclone separator '18,the conduit 21 coupled with the upper output portion of this separatoris also coupled to the input of a filter box 60, in the interior whichis disposed a collection receptacle 61 constructed of a suitable finemesh material (analogous to placement of a disposable bag within avacuum cleaner). Conduit 21 is coupled to the interior of the disposablereceptacle 61 so that fine particles can be entrapped within thereceptacle 6 1 and air can still pass through receptacle 61, theremainder of filter box 60 and downwardly through conduit 62 to ametering cock 63, which includes an adjustable screw or element 64 foradjusting the pressure balance of the system. The other side of themetering cock 63 is coupled through another conduit 65, an intake filter66, and conduit 67 to one side of pressure unbalance means 68. The otherside of pump 68 is coupled to conduit 14, and the pump is coupled, asindicated by the broken line 70, to a motor 71 which can be energizedover its input conductors 72, 73 to drive the pump 68 and draw air fromconduit 67 through the pump and displace the air under pressure throughconduit 14 to the input connection 13 of Venturi fitting 12.

General system operation When the general system of FIGURE 1 isenergized, electrical energy is supplied over conductors 72, 73 toenergize motor 71 and drive pump 68; electrical energy is supplied overinput conductors 56, 57 to drive motor 55 and in turn drive pump 52; andelectrical energy is also supplied over conductors 28, 30 to actuate thevibrating means of the second separator 23. In a preferred embodiment ofthe invention, valve 47 is of the solenoid type so that, upon initialenergization of the system, energy is temporarily supplied overconductors 74, 75 to actuate this valve and dump particles previouslycollected in box 46 downwardly through the valve and through conduit 24into the upper chamber of housing 10. This energization is removed andthe valve closed during subsequent operation of the system.

Air is displaced from pump 68 upwardly around the bend of conduit 14into the second input connection 13 of the Venturi unit 12. As is wellknown, the reduced pressure (due to the flow of air) provided interiorlyof the Venturi tube draws conductive ink particles downwardly from thereservoir :19 through the other input connection .11 of the Venturifitting, and an air stream with the conductive particles entrained isdisplaced out of the Venturi output connection 15, through conduit :16,and into the tangential input connection 17 of the cyclone separator 18. The pressure supplied at output port 20' is less than that at outputport 22. Thus particles passed in through input port 17 initially tendto circulate around the central portion of the separator in a pathdefined by the circular inside wall. The heavier particles then descenddownwardly to drop through output port 22 into the input portion of thesecond separator means 23. The particles which are lighter than thepredetermined mass (as determined by the setting of the pressure in thesystem) pass upwardly from cyclone separator 18 through outputconnection 20 and conduit 21 into the mesh-like receptacle 61 withinelutriation box 60. These lighter particles are the fines or minuteparticles such as paper debris, slitter dust, fragmented ink particles,etc., which accumulate in a system where a large amount of paper isdisplaced in the printing operation. The fines are entrapped within bag61 and the cleaned air is then displaced downwardly through conduit 62,metering cock 63 and conduit 65 to intake filter 66, where any strayparticles which may pass through receptacle 61 within the elutriationbox are trapped. The cleaned air is passed from filter 66 throughconduit 57 to the input side of pump 68.

As the ink particles fall downwardly from the end of conduit 22 into theend of the vibrator arrangement 23, the lateral vibration of this unitgradually displaces both the larger particles, retained above the mesh26, and the properly-sized conductive particles which fall through thismesh, to the right as shown in the drawing. The remaining conductiveparticles, all within the acceptable size range, pass onwardly throughconduit 34 down into the upper chamber 35 of the inker housing 10. Thelargerthan-desired particles, which in effect are coarse impurities,pass to the right over sieve 26, thence outwardly over lip 32 and fallunder the impetus of gravity for receipt in collection box 33.

The paper web, which has minute, discrete areas specifically charged torepresent a latent information-denoting pattern, is passed upwardly overroller 37 and downwardly to the right around the lower curved portion ofanvil or reference plate 36. As the charged portions of the web passupwardly they touch the mass of conductive ink particles and some of theparticles are attracted by electro-static force to the charged webareas. These particles are retained on the web as it is pulled upwardlyand to the left, over the upper lip portion of anvil 36 to emerge fromthe inker housing. Some ink particles may adhere to the unchanged areasof the tape to provide a slight background coloration which reduces theclarity and contrast of the desired image after fixing. Accordingly thesniffer head 41 is positioned to draw off the conductive particles fromthe background areas where a high-level charge has not been applied. Thetemporarilyinked, background-cleaned web then passes upwardly andbetween pressure-fixing rolls 38, 40, between which the particles arefirmly pressed into the surface of the dielectric web to provide apermanent record of the information originally denoted by the selectivechargers on the web.

The background particles removed through sniffer head 41 are pulledupwardly through tube 42 into the central or tangential input connection43 of cyclone separator 44. The heavier particles entering port 43 falldownwardly into collection box 46, and inasmuch as these particles fallwithin the appropriate range for inker use, they are retained in box 46until valve 47 is again opened. The lighter particles, representingfines or undesired portions of the material, are drawn upwardly throughport 45, conduit 48, and are trapped in filter 50. Air from this filteris pulled through conduit 51, pump 52, and tube 53 for discharge intothe atmosphere.

Inker housing Salient portions of the inker housing, including upperchamber 35 which retains the conductive, opaque particles for engagingthe charged portions of the web, are depicted in FIGURE 2. As thereshown the reference plate 36 is pivoted at its lower end portion over apivot arm 90 secured to a support 91 aflixed to support wall 92, and theupper portion of anvil 26 is likewise pivotally connected to another arm93 secured at its opposite end to a support 94 on the wall 92. With thisarrangement the anvil 36 can be displaced upwardly and to the left asindicated generally by the arrows 95, 96 to enable the operator of apage printer system embodying the novel inking system described hereinto readily thread the web into the inker station when the system isinitially conditioned for operation. Particles dropped downwardly fromtube 34 strike the curved portion of plate 97 which, together with plate98 at the opposite side of the input channel, deflects the particlesdownwardly into the main powder supply 100 within chamber 35 to providea supply of the powder particles for contacting the charged dielectricweb. Side late 97 is apertured ot define an overflow opening 101 in thesidewall through which particles can drop downwardly between walls 102,103 and into the main ink reservoir 19 and accumulate in a massdesignated 104. Aperture 101 is in effect an overflow vent through whichany excess accumulation of the particles are discharged into the mass104. Accordingly the level of the powder particles within the inker isalways kept at a predetermined level.

That portion of the powder mass which passes downwardly past aperture101 is constrained within the channel formed by portions 97, 98 and thelower portion of plate 97 is bent to define a first angled portion 105and a substantially horizontal portion 106 which is terminated in anarcuate lip 107. The extremity of lip 107 is positioned, with respect tothe lowermost portion of guide plate 98, so that the powder particlesfalling downwardly are aligned at an angle which causes the particles toassume a position indicated by slanted line 108, terminating below thelip 107. This angle is termed the angle of dynamic repose in the art,and is determined by the position at which the freely flowing particlescome to rest when dropped downwardly from a central point. Thus, evenwith the anvil 95 rotated upwardly out of the way and not engaging thepowder mass 100, when the system is initially loaded with powderparticles there is not an overflow over the lip 107 down into the mass104. Because the diameter of the particles used in the inking operationis very small, for example of the order of 50 microns, in the mass 100the particles behave much as a fluid so that after the anvil isdisplaced away from the body of the inker and the paper web is placedadjacent the inker structure, return of anvil 36 to the positionindicated in FIGURE 2 displaces the web into the operating position andthe powder mass 100 assumes the configuration shown.

A wind or air deflection assembly 110 is shown aflixed in the spacebetween deflection plate 98 and the dielectric web as it passes over therear of anvil 36. More specifically, deflector assembly 110 comprises abase plate 111 aflixed by a pair of screws 112, 113 to a support base(not visible) of the inker structure. The plurality of chevrons or airdeflector vanes 114 extend from the base 111 at substantially rightangles as also shown in FIGURE 3. As the web is displaced rapidlyupward, air is pulled along by friction to create a movement whichentrains a few of the powder particles in mass 100. The positioning andcurvature of the vanes 114 sets up semi-circular air currents,deflecting most of the air around the chevrons to drop the entrainedparticles back into the mass 100. It is also noted that, as the webemerges from the inker between the top of anvil 36 and lip 115 ofdeflector plate 98, the web is turned while the particles entrained inthe air tend to continue along a straight line to strike lip 115 anddrop downwardly into the mass 100 of the powder particles.

FIGURE 4 shows in more detail the discharge of the opaque conductiveparticles from the conduit which receives the appropriately sizedparticles from the second separating means 23. As there shown, theparticles are actually distributed through four separate input conduits34, 34A, 34B and 34C across the width of the inker between side walls116 and 117. Likewise in addition to a single overflow aperture 101, asvisible in FIGURE 2, FIGURE 3 shows there are actually five suchapertures 101, 101A, 101B, 101C and 101D spaced across the width of theinker housing.

A low ink Signal arrangement is provided within ink reservoir 19. Theindicator may comprise a pair of electrodes 77, 78 coupled to a pair ofconductors 80, 81 for attachment to a conventional resistance-measuringunit such as an ohmmeter. When the mass of conductive particles fallsbeneath the level required to maintain contact between plates 77, 78 thevalue of the effective resistance between these plates is changed toprovide a signal to associated equipment that the ink The snifferassembly shown in FIGURE 2 includes an upper member 120 which is aflixedto lower member 121 to define a plurality of channels for pulling airthrough input port 122, as air is pulled outwardly through conduit 123under the impetus of pump 52. Although the input area 122 appears as aport in FIGURE 2, FIG- URE 5 shows the general expanse of the input area122 which is actually a channel defined in the upper chamber 120 of theslitter assembly 41. A plurality of fastening screws 124 are passedthrough the apertured portions of upper member 120 for receipt in thecorrespondingly tapped portions of lower plate 121. The conduit 123 isconnected interiorly to a first lateral channel 125, in its turn coupledthrough a pair of connecting lateral channels 126 and 127 to the lateralchannel 128 near the front of lower member 121. This channel 128cooperates with the indented portion 122 of upper plate 120 to define aninput slot for drawing air from across the entire width of the inkedweb, to draw olf the background ink before the pressure-fixing step.This arrangement has proved very effective with the arrangementindicated in FIGURE 1, in that the web portions which should be inkedare selectively charged to voltage levels of 500 to 600 volts while thevalue of the random charges detected in the background area is of theorder of to 20 volts. Accordingly there is a variation of at least anorder of magnitude between the voltage level in the areas which shouldbe inked and the random aberrations of transient voltages found in thebackground areas which should be inked.

Venturi fitting As illustrated in FIGURE 6 the first input connection 11of the Venturi fitting includes a conical input section for connectionto the lower reservoir chamber 19 of the inker housing. Conductiveparticles within the conical section 11 are pulled downwardly throughthe arcuate portion 130 and discharged through the nozzle portion 131 ofthis input section, as air under pressure is provided through the otherinput connection 13 of the Venturi-type fitting. A joint 132 is providedto unite the input connections and define a suitable aperture for thefirst input section 11. Accordingly the air under pressure passes aroundthe portion of the first input connection in a manner better shown inFIGURE 7, which depicts separating ribs or supports 134 for bothpositioning the arcuate tapered portion of the first input connectionand directing the passage of air under pressure from the other inputconnection. The conductive particles entrained in the air stream arethen passed around curved portion 15 of the Venturi-type fitting fordisplacement through conduit 16 to the first separation means 18.

A cyclone separator, such as used for the first separation means, isalso employed as the means for recovering the usable particles from thesniffer arrangement. Such a separator is depicted in FIGURE 8. Thisstructure is now well known in the art and includes a tangential inputconnection 17 where the air stream with the particles entrained thereinis passed into the central body portion of separator 18 to receive agenerally circular motion around the wall. Lighter particles, or thoseof less than a predetermined mass, are represented by the broken line140, and heavier particles, which may include both particles of desiredsize and those of larger than desired size, are depicted by the solidline 141. In that a pressure lower than atmospheric pressure is providedto the upper input connection 20, the fines, or the higher impuritiesand particles of less than the desired mass, are drawn upwardly intoaperture 142 and through the first exit 20 for collection in theelutriation box 60 or the input filter 66 (FIGURE 1). Heavier particles,including the desired ink particles and those of larger than desiredmass, drop downwardly for discharge through the other output connection22 into the input portion of the vibrator separator. The particular massof the particles which will be drawn upwardly and those which will bedrawn downwardly can of course be adjusted by regulating the pressure inthe system, with suitable manipulation of adjustment screw 64 on themetering cock 63 in FIGURE 1.

To assist those skilled in the art to practice the invention, the valueof parameters measured during operation of a preferred embodiment of theinvention will be given. It is understood that these values are given byway of illustration only and in no sense by way of limitation.

In the preferred embodiment, as motor 71 was energized to operate pump68, about 2.2 cubic feet per minute (c.f.m.) of air was passed throughconduit 14 and through the system. There was a pressure drop of approximately 1% inches of water measured in the Venturi-like fitting 12.Conduits 16 and 22 were both of /2 inch inside diameter by inch outsidediameter. The input connection 17 of the first separation means 18 waspositioned 33 /2 inches above the bottom of Venturi-type fitting 12 anda pressure drop of about inch of water was measured in the conduit 16.There was only a minimal pressure drop in the cycline separtor 18. Ainch inside diameter by 1 inch outside diameter conduit 20 was providedto form the connection between the upper output port of the cycloneseparator and the larger conduit 21, which was 1 inch inside diameter by1% inches outside diameter. The pressure drop measured in theelutriation box 60 during operation was 2% inches of water.

Summary The inventive system provides a novel particulate materialhandling system, which may be used as the inking station for anelectrostatic printing system. The ink is transported by a completelypneumatic system to the ink ing position where the charged web picks upink particles. There is no mechanical handling of the ink throughout theclosed system. Not only does the pneumatic displacement of the inkparticles avoid damage to the fragile particles, but actually thequality of the ink particles in the inker itself has been determined tobe significantly improved over the quality of particles received fromthe manufacturer. Evidently this is caused by the continuingrecirculation of the ink which breaks up the agglomerates, reduces thesatelliting, and continuously refines the ink by removing the fineimpurities in the elutriation box 60 and in the input filter 66 whileconcomitantly eliminating the larger-than-desired impurities through thevibrator separator 23. This pneumatic transfer system for the inkedparticles has proved so successful in providing particles only of theappropriate size within the inking chamber that it may replacepreviously considered systems for processing and refining the inkparticles to insure there is no resin coating surrounding the carbon andto make certain that only particles of appropriate diameters areutilized in the inking process. The excess or background particlestrapped by the sniffer apparatus are returned periodically each time thesystem is energized, by simply opening a valve and dumping the particlesback into the inker chamber.

While only a particular embodiment of the invention has been describedand illustrated, it is apparent that various modifications andalterations may be made therein. It is therefore the intention in theappended claims to cover all such modifications and alterations as mayfall within the true spirit and scope of the invention.

I claim:

1. For use with an electrostatic printing system, an inker stationincluding a completely pneumatic transport system for delivering inkparticles within a predetermined size range and for refining theparticles to remove both particles smaller and particles larger than thedesired particles within the predetermined range, said stationcomprising:

a housing including an upper chamber and a lower reservoir chamber forcollecting particles which fall from the upper chamber, and a dielectricweb selectively charged to represent information thereon and mounted forpassage through said upper chamber which retains the particles tocontact the previously charged dielectric web;

a Venturi-type fitting with a first input connection coupled to thereservoir chamber, a second input connection for receiving air underpressure,- and an output connection through which a stream of air withconductive particles entrained therein is discharged;

a cyclone separator means including a tangential input connectioncoupled to the output connection of the Venturi-type fitting forreceiving the entrained particles together with the smaller and largerparticles, a first output connection for discharging the smallerparticles and a second output connection for dis charging both thedesired particles and the larger particles;

a filter, coupled to the first output connection of the cycloneseparator, for trapping said smaller particles;

a vibrator separator having an input portion for receiving both thedesired particles and the larger particles from the cyclone separatorincluding means for separating the larger particles from the desiredparticles, means for discharging the larger particles for receipt in acollection receptacle, and means in flow communication with said upperchamber of said housing for discharging the desired particles into saidupper chamber; and

a pump, having a high pressure side coupled to the filter and a lowpressure side coupled to the second input connection of the Venturi-typefitting, for providing the air under pressure to the Venturi-typefitting.

2. For use with an electrostatic printing system, an inker station forcontaining desired ink particles within a predetermined size range,particles smaller than the desired size and particles larger than thedesired size, said station comprising:

a housing an including an upper chamber and a lower reservoir chamberfor collecting particles which fall from the upper chamber, and adielectric web selectively charged to represent information thereon andmounted for passage through said upper chamber which retains theparticles to contact the previously charged dielectric web;

a Venturi-type fitting with a first input connection coupled to thereservoir chamber to receive particles, a second input connection forreceiving air under pressure, and an output connection for discharging astream of air with ink particles entrained therein;

a first separator means, including an input connection coupled to theoutput connection of the Venturi-type fitting for receiving theentrained particles together with the smaller and larger particles, afirs-t output connection for discharging the smaller particles and asecond output connection for discharging both the desired ink particlesand the larger particles;

a second separator means having an input portion for receiving both thedesired ink particles and the larger particles from the first separatorincluding means for separating the larger particles from the desired inkparticles, means for discharging the larger particles for receipt in acollection receptacle, and means in flow communication with said upperchamber of said housing for discharging the desired ink particles intosaid upper chamber;

filter means, coupled to the first output connection of the firstseparator, for trapping the smaller particles; and

pressure unbalance means, coupled between the filter means and thesecond input connection of the Venturi-type fitting, for pulling thesmaller particles from the first separator and for providing the airunder pressure to the Venturi-type fitting.

3. An inker station as set forth in claim 2 in which said filter meanscomprises a filter box with a removable bag therein for trapping andretaining the smaller particles received from the first separator means.

4. An inker station as set forth in claim 2 and further comprising ametering cock, coupled between the first output connection of the firstseparator and the pressure unbalance means, for adjusting the air flowthrough the system.

5. For use with an electrostatic printing system, an inker station forcontaining desired conductive particles within a predetermined sizerange, particles smaller than the desired size and particles larger thanthe desired size, said station comprising:

a housing including an upper chamber and a lower reservoir chamber forcollecting particles which fall from the upper chamber, and a dielectricweb having selectively charged areas representing a latent image andmounted for passage through said upper chamber which retains theconductive ink particles to contact the charged areas of the dielectricweb, the particles being attracted by and adhering to the selectivelychraged web areas to the web is displaced through at least a portion ofsaid housing;

a Venturi-type fitting with a first input connection coupled to thereservoir chamber to receive particles, a second input connection forreceiving air under pressure, and an output connection for discharging astream of air with ink particles entrained therein;

a first separator means, including an input connection coupled to theoutput connection of the Venturi-type fitting for receiving theentrained particles together with the smaller and larger particles, afirst output connection for discharging the smaller particles and asecond output connection for discharging both the desired ink particlesand the larger particles;

a filter, coupled to said first output connection of the first separatormeans, for trapping the discharged smaller particles;

a second separator means having an input portion for receiving both thedesired ink particles and the larger particles from the first separatormeans including means for separating the larger particles from thedesired ink particles, means for discharging the larger particles forreceipt in a collection receptacle, and means in flow communication withsaid upper chamber of said housing for discharging the desired inkparticles into said upper chamber;

suction means disposed adjacent the point at which the inked web emergesfrom the upper housing of the chamber to draw ofi unwanted particlesadhering to 1 1 background regions adjacent the selectively chargedareas; and

pressure unbalance means, coupled between the filter and the secondinput connection of the Venturi-type fitting, for pulling the smallerparticles from the first separator means and for providing the air underpressure to the Ven-turi-type fitting.

6. An inker station as set forth in claim 5 in which said suction meansdefines a slot extending substantially parallel to the plane of thecharged web and substantially normal to the direction of Web movement, athird separator means coupled to said slot for receiving the particlesfrom the slot, a second pressure unbalance means coupled to the thirdseparator means for removing the smaller particles from the thirdseparator means, and a collection means for receiving the remainingparticles from the third separator means.

7. An inker station as set forth in claim 6 and further comprising valvemeans coupled between the collection means of the third separator meansand the upper chamher of the housing for actuation to dump the collectedparticles back into the inker housing,

References Cited UNITED STATES PATENTS 797,080 8/1905 Smith 118-312 X2,540,348 2/1951 Reed 209-144 X 2,583,456 1/ 1952 Winquist 209-1442,779,468 1/ 1957 King 209-144 3,122,453 2/ 1964 Montgomery 118-6373,316,876 5/1967 'McCombie 118-312 X FOREIGN PATENTS 837,801 6/1960Great Britain.

FRANK W. LUTTER, Primary Examiner.

US. Cl. X.R.

